NASHVILLE, Tenn. — The president of the nation’s largest Protestant denomination on Tuesday vowed never to officiate at a same-sex union, and the Southern Baptist Convention called on the U.S. Supreme Court not to declare a constitutional right to same-sex marriage.

Pastor Ronnie Floyd was speaking to delegates at the convention’s annual meeting in Columbus, Ohio. But he said his message was also for the U.S. Supreme Court – which may rule within days on same-sex marriage – and for all of America.

Floyd said he has compassion for people whom he described as struggling with same-sex attraction, but he said it would be wrong to remain silent on the issue.

“America: We stand believing that marriage is the uniting of one man and one woman in a covenant commitment for a lifetime,” Floyd said to a standing ovation from the 5,000 people in attendance. “We do not need to redefine what God himself has defined already.”

The theme of Floyd’s address was “now is the time to lead,” a refrain he repeated several times. In addition to marriage, Floyd asked Southern Baptists to lead opposition to abortion, saying, “Even though reports state that abortion rates are down some, we do not need to become content in or callous to this deplorable issue.”

A recent Associated Press survey found that abortions have declined since 2010 not only in states where new laws make it harder to have them, but also in states where abortion rights are protected.

Floyd also called upon Christians to “decry all racism and prejudice, denouncing it as sin against God and sin against one another.”

But Floyd was especially fervent about marriage, saying: “This could be a watershed moment in our history … .”

The church leader’s address comes just a week after Southern Baptists announced that membership declined in 2014 for the eighth year in a row. Baptisms also were down to the lowest number since 1947.